1. Field of the Invention
The present invention relates to a stator for a reciprocating motor, and particularly, to a stator of a reciprocating motor capable of preventing deformation of a stator, which occurs during its fixation, and of reducing a size of a motor by widening an area of a magnetic flux.
2. Description of the Background Art
In general, a motor is used as a core driving source for most electrical and electronic products such as compressors, washing machines and electric fans. A motor receives electric energy and converts the electric energy into kinetic energy. There are a lot of kinds of motors, and it may be classified into a rotary motor that converts electric energy to a rotary force, a reciprocating motor that converts electric energy to a linear movement force, and the like.
Under circumstances of requiring a linear movement, the reciprocating motor which can implement a linear movement without any special equipment is suitable.
One example of such a reciprocating motor is shown in FIGS. 1 and 2. FIG. 1 is a front view showing one example of a conventional reciprocating motor, and FIG. 2 is its side view. As shown, the conventional reciprocating motor includes: a stator assembly 10 forming a flux, and a mover assembly 20 linearly reciprocating according to the flux of the stator assembly 10.
The stator assembly 10 includes: an outer stator 11 positioned outside the mover assembly 20 and formed as a cylindrical shape; and an inner stator 12 disposed inside the outer stator 11 at a certain distance (t) therebetween and formed as a cylindrical shape.
The outer stator 11 includes: a bobbin 13 in which a winding coil 30 is inserted; a plurality of core blocks 14 formed by laminating lamination sheets 17 having predetermined shapes on an outer surface of the bobbin 13 in a circumferential direction thereof; and a molding body 15 formed by molding outer surfaces of the core blocks 14 and an outer surface of the bobbin 13, which is not surrounded by the core blocks 14, for fixing the core blocks 14 to the bobbin 13.
The bobbin 13 is a hollow cylindrical body and is made of an insulation material such as plastic.
The core block 14 is formed in the following manner. “┌” shaped lamination sheets 17 are laminated and then are coupled to one side of the bobbin 13, and other lamination sheets 17 are laminated and then are coupled to the other side of the bobbin, facing the above-mentioned laminations sheets coupled to one side of the bobbin 13, so that a “” shaped core block 14 is formed. A plurality of core blocks 14 formed in such a manner are disposed in a circumferential surface of the bobbin.
An inner surface and an outer surface of each core block 14 become curved surfaces by a plurality of lamination sheets 17. The inner surfaces of the core blocks 14 coupled to the bobbin 13 form a circle, and their outer circumferential surfaces maintain regular intervals therebetween.
The mover assembly 20 includes: a mover body 21 movably disposed in an air gap between the outer stator 11 and the inner stator 12; and a plurality of magnets 22 fixed on an outer circumferential surface of the mover body 21 at regular intervals.
The conventional reciprocating motor as described above is operated in the following manner.
When a current is applied to a winding coil 30, a flux is formed around the coil 30. The flux forms a closed loop as it flows to the inner stator 12 along the outer stator 11. At this time, because the magnet 22 of the mover assembly 20 is put on the flux formed by the coil 30, the magnet 22 interacts with the flux of the winding coil 30 and thereby is pulled or pushed along a direction of the flux, allowing a linear reciprocation of the mover body 21.
In order to manufacture the reciprocating motor, first, a steel plate is cut into a plurality of laminations sheets 17 having predetermined shapes, and the plurality of lamination sheets 17 are laminated to thereby form a core block 14.
Next, a plurality of core blocks 14 are disposed on an outer surface of the bobbin 13 in which the winding coil 30 is inserted. Then, the bobbin 13 and the core block 14 are put in a special mold, and an over-molding is performed thereon by injecting a molding agent therein using a die casing method or an injection molding method. In such a manner, a molding body 15 is formed on an outer circumferential surface of each core block, thereby completing the outer stator 11. After that, an inner stator 12 is disposed at a certain distance (t) between itself and the outer stator 11, thereby completing the stator assembly 10.
FIG. 3 is a sectional view showing a coupling state of the outer stator of the conventional reciprocating motor. As shown, the reciprocating motor has a problem in that the core block 14 is deformed by being pressed in a central direction by molding pressure generated during injection of a molding agent and by contraction generated in hardening of a molding agent. For this reason, a distance (t) between the outer stator 11 and the inner stator 12 gets narrowed, thereby undesirably causing collision between the stator and the mover. Therefore, reliability and efficiency of the motor are degraded. Also, because the injection molding method is used in an over molding process in which a winding coil is coated with an insulation material, a molded object is contracted in cooling, causing a dimensional error, and ununiformity of a product is generated by a temperature of a mold, which increases a rate of defection. Also, a temperature of a mold and a pressure condition in an initial molding setting should be set. Therefore, there are several problems such as complicated manufacturing processes and an increased manufacturing cost.
Also, because there is an empty space between the core blocks, a width of each core block 14 should be widened to widen an area of a magnetic flux. Therefore, a size of the motor should be undesirably enlarged as much as the widened width.